Black said Trump had called him to say that he would be granted a full pardon, that his conviction was "unjust" and that he "should never been charged".

"The idea that I would commit a crime is a nonsense," Black told the BBC. He said that he was now "rebuilding my fortune, life goes on, this is a great occasion".

Black, who has called Trump a friend, published a book last year praising him, titled "Donald J. Trump: A President Like No Other."

He was found guilty in the United States in 2007 of scheming to siphon off millions of dollars from the sale of newspapers owned by Hollinger Inc, where he was chief executive and chairman.

When my assistant said there was a call from the White House, I picked up, said “Hello” and started to ask if this was a prank (suspecting my friends in the British tabloid media), but the caller spoke politely over me: “Please hold for the president.” https://t.co/8jdA7j5dMO

Black, a prolific writer and historian in his own right, vehemently maintained his innocence and launched a series of libel lawsuits in Canada to strike back at the detractors he blames for destroying his once vast empire.

But years of legal battles - which went all the way up to the US Supreme Court - failed to fully clear his name, although he did manage to greatly reduce his prison time by clearing himself of many of the charges.

Two of his three fraud convictions were later voided, and his sentence was shortened. He was released from a Florida prison in May 2012 and deported from the United States.

In 2013, the U.S. Securities and Exchange Commission banned Black from acting as a director of a U.S. company and ordered him to pay $4.1 million in restitution.